Rong Fu 30 z axis lock questions

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SlowLearner
Posts: 2
Joined: Tue Jun 23, 2015 9:03 pm

Rong Fu 30 z axis lock questions

Post by SlowLearner » Tue Feb 12, 2019 10:23 pm

I have had this mill drill for a few years now and it has an irritating issue, the cutter depth slowly moves downward while milling. I have gotten into the habit of holding the fine adjust with one hand while I crank the table with the other. Today I decided to see if I could fix the locking mechanism.

The mechanism consists of a threaded rod with a lever handle. Inside the casting there are two aluminum cylinders that the rod threads through. Each cylinder has a beveled side so when they are pulled together they exert force against the quill and lock it in place. I think the cylinders may have been shop made replacements but I purchased this from an estate so I got zero info at the time of purchase.

At first I thought that perhaps it just needed a shim between the lever side cylinder and the flange on the lever. I made one up and tried it and it actually seemed worse drifting down about .0015" in 6". One thing about the design that caught my attention when I had it apart is that both cylinders are threaded and I cannot quite comprehend how they are supposed to pull together. It seems to me that the cylinder on the lever side should have a clearance hole so it can float freely and thus actually tighten up. Do any of you who have one of these know how the factory parts were threaded? It just seems weird as it is.

The other thought I had is that the cylinders may actually be bottoming out against each other before there is enough tension on the quill.

Any comments on this are greatly appreciated.

Dave

armscor 1
Posts: 78
Joined: Sun Jun 12, 2016 3:12 am

Re: Rong Fu 30 z axis lock questions

Post by armscor 1 » Wed Feb 13, 2019 12:54 am

The cylinder, cam on the right hand side is threaded, LHS must have clearance.
I replaced the cast iron cams on my machine with aluminium to prevent marring on the quill.

SlowLearner
Posts: 2
Joined: Tue Jun 23, 2015 9:03 pm

Re: Rong Fu 30 z axis lock questions

Post by SlowLearner » Wed Feb 13, 2019 9:13 am

Thank you, that is what I suspected. I found a video on youtube that has some detail on it, it is put out by That Lazy Machinist. I also found images of the same parts for a Bridgeport and they have clearance on one side and threads on the other.

Dave

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